Alkylene oxide reaction product with polyphosphoric acids



United States Patent 3,369,060 ALKYLENE OXIDE REACTION PRODUCT WITHPOLYPHOSPHORIC ACIDS Paul E. Pelletier, Bartlett, and Floy Pelletier,Lockport, Ill., assignors to Wyandotte Chemicals Corporation, acorporation of Michigan No Drawing. Original application Aug. 28, 1959,Ser. No. 836,580. Divided and this application Aug. 4, 1966, Ser. No.570,175

12 Claims. (Cl. 260-933) The present application is a division of ourcopending application Ser. No. 836,580, filed Aug. 28, 1959, entitledPolyurethane Compositions.

The present invention relates to polyurethane compositions produced byreaction of polyisocyanates with hydroxy compounds produced by reactionof alkylene oxides with certain selected phosphorus-containing acids.The invention includes mixtures of polyisocyanates with the alkyleneoxide-phosphorus acid reaction products as well as the polyurethaneresins possessing improved resistance to burning and flame propagationwhich may be produced therefrom. Outstanding results are obtained whenthe polyurethane resin-producing reaction takes place in the presence ofwater or other blowing agent to produce polyurethane foams which arecharacterized by non-inflammability and the capacity to self-extinguishfires.

In accordance with the invention an alkylene oxide is reacted with aphosphorus-containing acid which corresponds to a mixture of phosphoruspent-oxide and water containing from 75 to 90% by weight of phosphoruspentoxide with from -25% by weight of water. Representativephosphorus-containing acids which are usable are metaphosphoric acid andpyrophosphoric acid. Additionally, various mixtures prepared bydissolving phosphorus pentoxide in water to provide phosphoruspentoxide-water mixtures within the range of proportions specified maybe used. In these mixtures, the phosphoruscontaining acids which may beformed by dissolution of the phosphorus pentoxide in water may exist inpolymeric form. Partial esters such as partial alkyl esters of the abovedefined phosphorus-containing acids may also be used so long asesterification of the acid leaves a residue of at least one OH group perphosphorus atom in the acid. Partial esters are illustrated by themonoand diesters of pyrophosphoric acid, such as dimethyl acidpyrophosphate and monoethyl acid pyrophosphate.

The alkylene oxides which may be used are preferably illustrated byethylene oxide, propylene oxide, butylene oxide and styrene oxide. Thepreferred oxides contains the 1,2 epoxy group, but the invention is notso limited and 2,3 butylene oxide may be used. The invention includesepichlorohydrin and other halohydrins such as epiiodohydrin,epifluorohydrin, epibromohydrin, etc., and higher molecular weightoxides such as octylene oxide as Well as dioxides (diepoxides)illustrated by the diglycidyl ether monomer of bisphenol A. Halogenatedalkylene oxides such as epichlorohydrin may also be used.

It is known as taught, for example, in United States Patent 2,372,244,to react phosphoric acid or phosphorus acid with olefin oxides toproduce reaction products possessing primary hydroxyl groups asindicated by the reaction equations set forth in said patent.

The products of the invention are very different from those of Patent2,372,244 since when sufiicient propylene oxide is reacted withphosphoric acid or phosphorus acid (about 6 mols of oxide per mol ofacid) to produce a neutral product sufiiciently reactable withpolyisocyamates for polyurethane foam production, the foam product isnot self-extinguishing or non-inflammable. Using the phosphoruspentoxide-water mixtures specified by the invention, reaction withalkylene oxides may be efiected to provide at least substantiallyneutral products which are reactive with polyisocyanates to formnon-inflammable and self-extinguishing polyurethane foams.

At least one epoxy equivalent of alkyleneoxide is reacted with eachhydroxyl equivalent of the phosphoruscontaining acid. Preferably, thereaction is continued further to provide an at least substantiallyneutral reaction product in which at least two epoxy groups are reactedper hydroxy equivalent in the starting phosphorus-containing acid.

The reaction products of the invention are hydroxycontaining materials.These may be used along for reaction wtih polyisocyanates or inadmixtures with other compounds reactive with polyisocyanates such ashydroxycontaining polyesters and polyethers. Whatever proportion of thereaction product of the invention is used in the mixture provides animprovement in fire resistance and it is preferred to use enough toprovide self-extinguishing characteristics to the foam product. Theself-extinguishing characteristic is determined in accordance withmethod D365-56T of the American Society for Testing Materials.

The reaction of alkylene oxides with phosphorus-containing acids inaccordance with the invention can be performed at various pressures,atmospheric and superatmospheric pressures, and the temperatureofreaction can vary from 50 to 500 'F. Low temperature operation, whilepossible, is inconvenient because the reaction is exothermic andproceeds more rapidly as the temperature is increased. Temperaturesabove 220 F., though useful, are less desirable because the productstend to darken. Preferred reaction temperature is within the range of190 F. providing an easily controlled reaction without darkening of theproduct.

The reaction is preferably effected by incremental addition of thealkylene oxide to the hot phosphorus-containing acid, though this is notessential. Desirably, the phosphorus-containing acid is maintained at atemperature of 90-120" by cooling while the alkylene oxide is added.This prevents local over-heating and excessive reaction temperaturewhich may result from the exothermic reaction. After the alkylene oxideaddition has been completed and the reactants intimately mixed togetherby stirring, the temperature is desirably raised slowly to the preferredreaction temperature and held at this temperature until the reaction has:been completed. Completion of the reaction may be determined by thesubstantial exhaustion of alkylene oxide from the reaction mixture or,conveniently, by the achievement of a substantially neutral pH. Anyslight excess of alkylene oxide which may be present at the completionof the reaction can be removed by heat under vacuum.

The invention is illustrated in the following examples:

EXAMPLE I Phosphorus pentoxide is added to water with constant stirringwith external cooling and addition is continued until 3.94 parts ofphosphorus pentoxide are dissolved per part of water. Thephosphorus-containing acid so produced is a viscous, clear and highlydense liquid from which .pure pyrophosphoric acid crystallizes onstanding.

426 grams of the phosphorus-containing acid soproduced is placed in atwo liter flask and heated to 90120 F. with stirring whereupon 1588grams of 1,2 propylene oxide is added continuously while the flask iscooled to maintain a temperature of from 90-120 F. In this way, 27.4mols of propylene oxide is mixed with 9.6 hydroxy equivalents of thephosphorus-containing acid. After all the propylene oxide is added (theexotherm decreases toward the end of the propylene oxide addition) thetemperature is raised slowly to 170 F. and held at this temperature for1% hours. The

product at this point is essentially neutral upon titration and containsa slight excess of propylene oxide which is removed by application ofvacuum while maintaining a temperature of l50l70 F.

The final yield is 1911 grams corresponding to the reaction of 25.6 molsof propylene oxide and providing a product in which the ratio of reactedepoxy group to hydroxyl radical in the initial phosphorus-containingacid is about 2.7: l. The product has an actual hydroxyl number byacetylation method of 275, acidity of O, and a viscosity of 1440centipoises measured at 77 F.

EXAMPLE II A typical foaming composition was prepared using the hydroxycompound obtained in Example I as follows:

Quasi prepolymer composition Parts:

32.1 Hydroxy compound of Example I.

67.9 Toluene diisocyanate (80/20 mixture of the 2,4 and 2,6 isomers).Mixed and allowed to exotherm while stirring for 50 minutes, heat to 200F. for 25 minutes and then allow to cool to room temperature. AnalyzedNCO 21.2%.

Foaming mixture Parts:

50.9 Quasi prepolymer composition.

15.3 Trichloromonofluoromethane (blowing agent).

26.6 Polyester resin produced by condensing adipic acid with ethyleneglycol to provide a condensate having an hydroxyl number of 480.

6.69 Hydroxy compound of Example I.

.24 Triethylamine.

.27 -Wetting agent-Silicone X-520 (Union Carbide and Carbon) a dimethylend-blocked silicone.

The composition set forth above foams to produce a very fine celled foamproduct having excellent tensile strength and load bearing qualities. Itis self-extinguishing according to ASTM Method D635-56T.

It will be observed that the foaming composition of Example II includesa proportion of a polyester which functions to improve the physicalproperties of the foam product. Various polyesters or polyethers may beused having an hydroxyl number in the range of 250 to 700 in order toimprove the physical properties of the foam product.

Polyesters of polycarboxylic acids with polyols such as glycols arepreferred, the glycol reactant being used in excess to provide hydroxylfunctionality in the desired range. Polyethers may also be used such. ashigh molecular weight epoxy resins in which the repeating unit containssecondary hydroxyl groups. Similarly, esters of these epoxy resins inwhich the epoxy groups are reacted but the hydroxyl groups are unreactedare also suitable.

From 15 to 60 parts of the polyester or polyether component is desirablyused for every 85 to 40 parts of the hydroxy compounds of the inventionwhich are present in the foaming mixture. These polyesters or polyetherspreferably possess an hydroxyl number of from 450 to 480.

It will be appreciated that the polyester component can be omitted fromExample II while still providing selfextinguishing foams although thefoam products possess less desirable tensile strength and load bearingproperties.

EXAMPLE III Phosphorus pentoxide is added to water with constantstirring with external cooling and addition is continued until 4.73parts of phosphorus pentoxide are dissolved per part of water. Thephosphorus-containing acid so produced is a viscous, clear and highlydense liquid.

400 grams of the phosphorus-containing acid soproduced is placed in atwo liter flask and heated to a -120 F. with stirring whereupon 1500grams of 1,2 propylene oxide is added continuously while the flask iscooled to maintain a temperature of from 90-120 F. In this way, 25.9mols of propylene oxide is mixed with 7.75 hydroxy equivalents of thephosphorus-containing acid. After all the propylene oxide is added thetemperature is raised slowly to 160 F. and held at this temperature for1 hour. The product at this point is essentially neutral upon titrationand contains a slight excess of propylene oxide which is removed byapplication of vacuum while maintaining a temperature of 150 F. Thefinal yield is 1700 grams corresponding to the reaction of 22.4 mols ofpropylene oxide and providing a product in which the ratio of reactedepoxy group to hydroxyl radical in the initial phosphorus-containingacid is about 2.9: 1. The product has an actual hydroxyl number byacetylation method of 248 and a viscosity of 1,620 centipoises measuredat 77 F.

EXAMPLE IV Foaming mixture Parts Quasi prepolymer composition. 15 .93

Trichloromonofluoromethane (blowing agent).

Polyester resin produced by condensing adipic acid with ethylene glycolto provide a condensate having an hydroxyl number of 480.

Triethylamine.

Wetting agent-Silicone X-520 (Union Carbide and Carbon) 21 dimethylend-blocked silicone.

The composition set forth above foams to produce a very fine celled foamproduct having excellent tensile strength and load bearing qualities. Itis self-extinguishing according to ASTM Method D635-56T.

It will be understood that the production of the polyurethane foam maybe accomplished in various ways known to the art, the foam productionillustrated in Examples I-IV being simply illustrative. In this regard,reference is made to the text entitled Polyurethanes by Bernard A.Dombrow, published by Reinhold Publishing Corporation, 1957, wherereference is made to various techniques for the production ofpolyurethane foams, including the one-shot procedure as well as variousprocedures including polyurethane prepolymers.

The following is a further example of a method of forming a hydroxycompound in accordance with the invention which may be reacted with apolyisocyanate as in Example II or Example IV to produce aself-extinguishing polyurethane composition as herein described.

EXAMPLE V A two liter, three neck flask was fitted with a refluxcondenser, stirring motor, thermometer, and addition tube connected to aseparatory tunnel for continuous addition of epichlorohydrin.

Triphosphoric acid was first prepared by adding slowly, 61.8 parts byweight of phosphorus pentoxide to 38.2 parts by weight of a 75%orthophosphoric acid solution. Constant stirring is necessary tocompletely react or dissolve the oxide. The temperature should be keptbelow 220 F. during the first addition of oxide to prevent excessivewater vapor loss.

348 gins. or 1.35 moles of the above acid were weighed into the twoliter flask and about 1340 gins. or 14.5 moles of epichlorohydrin wereadded continuously at a temperature of l60180 F. After all theepichlorohydrin was added, the product was heated to 250 F. for twohours. At the end of this reaction, the product titrated neutral withsodium hydroxide. Any excess, unreacted epichlorohydrin was removed byvacuum distillation at 250 F.

The final yield was 1670 gms. which indicates that 1430 moles ofepichlorohydrin were added.

The final product has a pH of 5 but titrates as an essentially neutralcompound. It is a clear, wine colored liquid which is insoluble in waterand soluble in alcohol. Its hydroxyl number is 226. Similar productshaving a pH ranging from 2 to 6 are useful in accordance with theinvention.

In a foam producing mixture in accordance with the invention, the statedpresence of a polyisocyanate component is intended to include thepolyisocyanate compound per se, such as toluene diisocyanate, or areaction product of the polyisocyanate which liberates freepolyisocyanate when heated, such as a compound with phenol, or aquasiprepolymer of the monomeric polyisocyanate which providesisocyanate polyfunctionality, such as the prepolymers illustrated in thepresent examples.

Any polyisocyanate will react with the hydroxy compounds of theinvention such as toluene diisocyanate (pure or mixed isomers),hexamethylene diisocyanate, 1,5- naphthalene diisocyanate, methylenebis-4-phenyl isocyanates, etc., however the preferred isocyanates arethe various commercial toluene diisocyanates because of theiravailability and desirable physical properties which are well understoodby the art.

As is conventional, the foaming composition includes a blowing agent.This term includes various types of materials which are known to possessan expanding function. Thus, water reacts with isocyanate to producecarbon dioxide gas thereby providing a blowing agent which enters intothe polymerization reaction providing an internal blowing agent.External blowing agents which expand or decompose to yield gaseousproducts, normally upon increase in temperature, may also be used. Theseare termed external agents because they do not enter into the isocyanatepolymerization reaction. External blowing agents are illustrated by thematerial generally known as Freons which are lower molecular weighthydrocarbons usually containing both fluirine and chlorinesubstitutents. Other external blowing agents are illustrated by sodiumand ammonium bicarbonate, etc.

As is generally accepted in the urethane art when preparing a foam theequivalents of isocyanate are preferably approximately equal to theequivalents of hydroxyls (or other radicals providing active hydrogen)designed to react with the polyisocyanate to produce the urethanepolymer. The ratio of isocyanate to hydroxyl can vary considerably inaccordance with the invention in the same manner as is known for theconventional hydroxyl-containing materials known to the art.

The invention is defined in the claims which follow.

We claim:

1. A composition of matter comprising the substantially neutral hydroxyreaction product of an oxide selected from the group consisting ofethylene oxide, propylene oxide, butylene oxide and styrene oxide with aphosphorus acid selected from the group consisting of phosphorus acidswhich correspond to a mixture of from -90% by weight of phosphoruspentoxide with from 10-25% by weight of water and partial alkyl ethersof said acids having a residue after esten'fication of at least one OHgroup per phosphorus atom, said hydroxy reaction product containing atleast one reacted epoxy group per hydroxyl equivalent of said acid.

2,. The reaction product claimed in claim 1 which contains from 2.7-2.9reacted epoxy groups per hydroxyl equivalent of said acid.

3. A composition of matter comprising the substantially neutral reactionproduct of an oxide selected from the group consisting of ethyleneoxide, propylene oxide, butylene oxide and styrene oxide with aphosphorus acid which corresponds to a mixture of from 7590% by weightof phosphorus pentoxide with from 10-25% by weight of water.

4. A composition of matter as recited in claim 3 in which said oxide ispropylene oxide.

5. A composition of matter as recited in claim 3 in which said acid istriphosphoric acid.

6. A composition of matter as recited in claim 3 in which said acid ispyrophosphoric acid.

7. A composition of matter comprising the substantially neutral hydroxyreaction product of an alkylene oxide with a phosphorus acid selectedfrom the group consisting of phosphorus acids which correspond to amixture of from 75-90% by weight of phosphorus pentoxide with from10-25% by weight of water and partial alkyl esters of said acids havinga residue after esterification of at least one OH group per phosphorusatom, said hydroxy reaction product containing at least one reactedepoxy group per hydroxyl equivalent of said acid.

8. A hydroxyalkyl polyphosphate produced by the reaction of apolyphosphoric acid which corresponds to a mixture of from 75-90% byweight of phosphorus pentoxide with from 1025% by weight of water with astoichiometric excess of a vicinal monoepoxide.

9. A hydroxyalkyl polyphosphate produced by the reaction of apolyphosphoric acid with a stoichiometric excess of a vicinalmonoepoxide, said vicinal monoepoxide being ethylene oxide.

10. A hydroxyalkyl polyphosphate produced by the reaction of apolyphosphoric acid which corresponds to a mixture of from 7590% byweight of phosphorus pentoxide with from l025% by Weight of water with astoichiometric excess of a vicinal monoepoxide, said vicinal monoepoxidebeing propylene oxide.

11. A hydroxylalkyl polyphosphate produced by the reaction of apolyphosphoric acid which corresponds to a mixture of from 7590% byweight of phosphorus pentoxide with from 10-25% by weight of water witha stoichiometric excess of a vicinal monoepoxide, said vicinalmonoepoxide being epichlorohydrin.

12. A hydroxyalkyl polyphosphate produced by the reaction at atemperature of from 50-500 F. of a poly phosphoric acid whichcorresponds to a mixture of from 75-90% by weight of phosphoruspentoxide with from 10-25% by weight of water with an excess of avicinal monoepoxide sufiicient to produce a substantially neutralproduct.

References Cited UNITED STATES PATENTS 2,979,523 4/1961 Cantrall et al260-978 X CHARLES B. PARKER, Primary Examiner.

A. H. 'SUTTO, Assistant Examiner.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3 ,369,060 February 13 1968 Paul E. Pelletier et al It is hereby certifiedthat error appears in the above numbered patent requiring correction andthat the said Letters Patent should read as corrected below.

Column 2 line 12 for "along" read alone line 13 for "wtih polyi s ocyanates or in admixtures" read with polyisocyanates or in admixtureline 21 for "D365-56T" read D635-56T column 5 lines 39 and 40 for"isocyanates" read isocyanate line 55, for "material" read materialsline 57 for fluirine" read fluorine column 6 line 6 for "ethers" readesters line 43 after "acid" insert which corresponds to a mixture offrom 75-90% by weight of phosphorus pentoxide with from 10-25% by weightof water Signed and sealed this 29th day of April 1969 (SEAL) Attest:

EDWARD M.FLETCHER,JR. EDWARD J. BRENNER Attesting Officer Commissionerof Patents

1. A COMPOSITION OF MATTER COMPRISING THE SUBSTANTIALLY NEUTRAL HYDROXY REACTION PRODUCT OF AN OXIDE SELECTED FROM THE GROUP CONSISTING OF ETHYLENE OXIDE, PROPYLENE OXIDE, BUTYLENE OXIDE AND STYRENE OXIDE WITH A PHOSPHORUS ACID SELECTED FROM THE GROUP CONSISTING OF PHOSPHORUS ACIDS WHICH CORRESPOND TO A MIXTURE OF FROM 75-90% BY WEIGHT OF PHOSPHORUS PENTOXIDE WITH FROM 10-25% BY WEIGHT OF WATER AND PARTIAL ALKYL ETHERS OF SAID ACIDS HAVING A RESIDUE AFTER ESTERIFICATION OF AT LEAST ONE OH GROUP PER HOSPHORUS ATOM, SAID HYDROXY REACTION PRODUCT CONTAINING AT LEAST ONE REACTED EPOXY GROUP PER HYDROXYL EQUIVALENT OF SAID ACID. 